TransJeju Jeju 100K

Overall score 2.9Good
Thin evidence2 sources#52 of 61 ultras

Seogwipo, South Korea · 104 km (64.6 mi) · 4,000 m (13,120 ft) gain

Race day Sat 3 Oct 2026

Website (opens in a new tab)

Is it right for you?

Footing
Technical1.5
Climbing
Hilly1.9
Overall cutoff
Normal3.3
Intermediate cutoffs
Reasonable3.0
Crew access
Some points3.0
First timer friendly
Demanding2.2

Footing and climbing are course traits: 5 is the smoother, flatter end, not a better race.

Watch out: Slippery rock and long stairs demand specific preparation All 3

Held back by race (2.1) and course (2.3).

Best for

Provisional: based on 2 sources. Why

Ran it? Your rating helps.

Score breakdown

Every score is out of 5, and 5 is always the better end.

Each bar is a range of 0.25 points; the light bar holds this race. The average race scores 3.4.

What does this score mean?

Why runners love it

  • Hallasan mountain trails and volcanic scenery
  • Fellow runners offered practical help to a novice finisher

Watch out for

  • Slippery rock and long stairs demand specific preparation
  • Poles are prohibited
  • Historical crew directions caused confusion

Latest or next race

Sat 3 Oct 2026

Official race site(transjeju.utmb.world, opens in a new tab)
Climbing
4,000 m (13,120 ft)
Cutoff
29 hours
Pace needed
26:54 per mi (16:43 per km)

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What runners say

Overall score 2.9 out of 5

2 reviews and race reports

2 reviews

  • Jo Meek

    Raced 2025 · Jo Meek

    Tone: Mixed

    Meek describes a difficult Jeju 100K edition with slippery rocks, roots, long stairs and crowded hiking trails. She took an early wrong turn and her crew encountered misleading checkpoint directions, but finished fifth woman. Her 2025 result is matched to the 104 km (64.6 mi) distance, not the separate longer race.

    Covers Support, Course, Conditions, Stay and travel

    Read on jomeekblog.wordpress.com (Jo Meek, opens in a new tab)

  • ejump0

    Raced 2023 · Reddit: first TransJeju finish

    Tone: Mixed

    A first-time runner at this distance finished the 2023 edition in 22:57. Cold rain, wind, slippery rock and steep stairs made progress difficult; other runners helped when lighting failed. The report describes the historical 28-hour limit, not the current 29-hour allowance.

    Covers Course, Conditions, Cutoffs

    Read on reddit.com (Reddit: first TransJeju finish, opens in a new tab)
Ran TransJeju Jeju 100K? Rate it

Pick a score, then tell the next runner about the footing, cutoffs and aid stations.

Scores

Open a category for its ratings and the evidence behind them.

Below par. How runners feel about it, how well it is run, and the community around it. Counts for 25% of the overall score.

Toughness for its distance: Very tough

  • Runner satisfactionLoved3.9

    Both finishers value the achievement while describing substantial discomfort. · Low confidence

  • OrganizationAdequate3.1

    One report describes an early wrong turn and confusing crew directions. · Low confidence

  • Community and vibeWarm4.0

    A novice finisher received practical help from other runners. · Low confidence

Good. Aid stations, crew access, drop bags and pacer rules. Counts for 25% of the overall score.

  • Aid stationsStandard3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • Crew accessSome points3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • Drop bagsSome stations3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • PacersLate race3.0

    Few accounts establish this aspect for the current edition. · Low confidence

Below par. Course marking, scenery, and how runners rate the trail itself. Counts for 15% of the overall score.

  • Course markingMostly clear3.1

    An experienced runner reports an early wrong turn; one account cannot establish a recurring problem. · Low confidence

  • SceneryBeautiful4.2

    Mountain trails and Hallasan landscapes feature prominently in the accounts. · Low confidence

  • Trail experienceFine3.3

    Mountain terrain appeals, but slippery steps and hiking traffic complicate the experience. · Low confidence

Course traits, not part of the score

  • FootingTechnical1.5

    Both reports describe slippery rocks, roots and long stair sections. · Medium confidence

  • RunnabilityLots of hiking2.1

    Technical footing and steep stairs repeatedly interrupt running. · Medium confidence

  • ClimbingHilly1.9

    Climbs 203 ft per mi (38 m per km), from the recorded elevation gain. · High confidence

Good. Race-day temperature and how predictable the weather is. Counts for 14% of the overall score.

  • Race-day temperatureHarsh2.3

    Both accounts encountered uncomfortable wet conditions. · Low confidence

  • Weather reliabilityVariable2.5

    Two wet editions do not establish predictable conditions. · Low confidence

Course traits, not part of the score

  • AltitudeModerate3.0

    Few accounts establish this aspect for the current edition. · Low confidence

Good. How generous the overall and intermediate cutoffs are for the terrain. Counts for 13% of the overall score.

  • Overall cutoffNormal3.3

    The 29-hour allowance offers time, but slippery terrain can substantially reduce pace. · Low confidence

  • Intermediate cutoffsReasonable3.0

    Few accounts establish this aspect for the current edition. · Low confidence

Not part of the score

  • First timer friendlyDemanding2.2

    A first-distance finisher succeeded, but wet technical footing and overnight fatigue were demanding. · Medium confidence

  • Getting inSells out3.0

    Few accounts establish this aspect for the current edition. · Low confidence

Good. Getting there, places to stay, race-day logistics and value. Counts for 8% of the overall score.

  • Travel easeFair3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • Places to stayBook early3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • LogisticsSome complexity3.0

    Few accounts establish this aspect for the current edition. · Low confidence

  • ValueFair3.0

    Few accounts establish this aspect for the current edition. · Low confidence

Course

Route, 104 km (64.6 mi)

Surface
Trail
Climbing
4,000 m (13,120 ft)
Climb rate
Mountain, 39 m per km (203 ft per mi)
Night
Some
Start
05:00

Cutoffs and aid

Overall cutoff
29 hours
Pace needed
26:54 per mi (16:43 per km)

Getting in

Qualifies for
  • UTMB Running Stones

Footing, aid and entry notes in full

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Key facts

Checked against the 2026 edition on the official race site. Rules change, so confirm before you enter.

Location
Seogwipo, South Korea
Region
Outside the US
Typical month
October
Footing
Wet volcanic rocks, roots, wooden steps and mountain trails require deliberate foot placement.
Cutoff rules
Current intermediate cutoff details were not verified. Consult the edition-specific runner information before planning a pace.
Aid and crew
Unverified current support arrangements are left unknown.
Mandatory gear
Official list includes two headlamps, spare batteries, phone, warm and waterproof layers, gloves, hat, whistle, food, cup and at least 1 L (34 fl oz) water. Poles are prohibited; consult the complete list.

Sources

Pages we used for facts and ratings. See how we rate ultras.

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